Targeting Aberrant Glutathione Metabolism to Eradicate Human Acute Myelogenous Leukemia Cells

Shanshan Pei,Sarah J Neering,Mohammad Minhajuddin,Kevin P Callahan,Michael W Becker,Fred K Hagen,Joshua Munger,Jane L Liesveld,Lei Shi,John M Ashton,Peter A Crooks,Patricia Greninger,Craig T Jordan,Jeffrey Settleman,Eleni D Lagadinou,Haobin Ye,Marlene Balys,Cheryl A Corbett ,Cyril H Benes ,Kristen M O’dwyer ,Lu Zheng

doi:10.1074/jbc.m113.511170

Abstract

The development of strategies to eradicate primary human acute myelogenous leukemia (AML) cells is a major challenge to the leukemia research field. In particular, primitive leukemia cells, often termed leukemia stem cells, are typically refractory to many forms of therapy. To investigate improved strategies for targeting of human AML cells we compared the molecular mechanisms regulating oxidative state in primitive (CD34(+)) leukemic versus normal specimens. Our data indicate that CD34(+) AML cells have elevated expression of multiple glutathione pathway regulatory proteins, presumably as a mechanism to compensate for increased oxidative stress in leukemic cells. Consistent with this observation, CD34(+) AML cells have lower levels of reduced glutathione and increased levels of oxidized glutathione compared with normal CD34(+) cells. These findings led us to hypothesize that AML cells will be hypersensitive to inhibition of glutathione metabolism. To test this premise, we identified compounds such as parthenolide (PTL) or piperlongumine that induce almost complete glutathione depletion and severe cell death in CD34(+) AML cells. Importantly, these compounds only induce limited and transient glutathione depletion as well as significantly less toxicity in normal CD34(+) cells. We further determined that PTL perturbs glutathione homeostasis by a multifactorial mechanism, which includes inhibiting key glutathione metabolic enzymes (GCLC and GPX1), as well as direct depletion of glutathione. These findings demonstrate that primitive leukemia cells are uniquely sensitive to agents that target aberrant glutathione metabolism, an intrinsic property of primary human AML cells.

Highlights

Eradication of primary human leukemia cells represents a major challenge
The development of strategies to eradicate primary human acute myelogenous leukemia (AML) cells is a major challenge to the leukemia research field
Our data indicate that CD34؉ AML cells have elevated expression of multiple glutathione pathway regulatory proteins, presumably as a mechanism to compensate for increased oxidative stress in leukemic cells

Summary

Conclusion

Aberrant glutathione metabolism is an intrinsic property of human leukemia cells. Significance: Interventions based on modulation of glutathione metabolism represent a powerful means to improve therapy. These findings demonstrate that primitive leukemia cells are uniquely sensitive to agents that target aberrant glutathione metabolism, an intrinsic property of primary human AML cells. Targeting Aberrant Glutathione Metabolism in AML to better understand the underlying biology of oxidative state, and the properties that make cells susceptible to redox perturbation, we evaluated the characteristics of primary human hematopoietic cells derived from patients with acute myelogenous leukemia (AML) in comparison to normal controls. Our findings indicate agents such as parthenolide (PTL) and piperlongumine (PLM) have a dramatic inhibitory effect on the leukemic glutathione system, whereas only a limited and transient perturbation in normal cells This preferential effect is strongly linked to their selective toxicity toward leukemia and other cancer cell types. We propose that therapeutic targeting of glutathione metabolism represents a potentially powerful strategy to induce selective toxicity toward a broad range of primary leukemia cells, including malignant stem and progenitor populations

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION